Talking Tall Rounds: Abdominal Aortic Graft Infection - Emphasizing a Team Approach to Patient Care Coordination

Podcast Transcript

Announcer:
Welcome to the Talking Tall Rounds series, brought to you by the Sydell and Arnold Miller Family Heart, Vascular and Thoracic Institute at Cleveland Clinic.

Sean Lyden, MD:
I want to welcome everybody to Heart and Vascular Thoracic Institute Tall Rounds. Today, we're actually going to do, emphasizing one of the things I think we do really well here. It's a team approach to patient care, and I'm very excited to be the moderator today. We're going to talk about a patient that came through the vascular surgery service with an aortic graft infection and good, bad, or indifferent, it also required the help of multiple other services as well as our advanced practice personnel. So with no further ado, we'll try and get started here on time and I'm going to first invite up Dr. David Laczynski, who's one of our vascular residents who's going to first introduce the case. Dr. Laczynski.

David Laczynski, MD:
I'll be talking about a patient that we had the privilege of taking care of last month. This is a 72-year-old gentleman who had presented to an outside hospital with two weeks of severe fatigue and nausea that culminated in a fall at home. His past medical history was notable for a ruptured aortic aneurysm, for which he underwent an endovascular aortic repair at an outside hospital in May. This was in July. His course was complicated by bacteremia and a groin infection that had grown bacteroides. He was put on a 10-day course of IV antibiotics and from the outside notes, it looks like it was terminated early due to patient wishes.

David Laczynski, MD:
Past medical history is as listed, he had COPD and was a former longtime smoker. Other than the EVAR that he had undergone, no other surgical history. On review of systems, we found that he had had a 40-pound weight loss over the prior two months and on presentation, he was afebrile, non-toxic. His abdomen was soft and nontender and he had palpable pulses all the way down to the feet. Labs were notable for a slight leukocytosis and elevated sed rate. Kidney function was normal. He underwent a CT head just due to the fall. They found no acute pathology. In addition, he underwent a CT angiography that as you can see in the images here on both the axial and the coronal cuts that are foci of gas in the aneurysm sac surrounding the known endograft.

David Laczynski, MD:
And as well on the right side, you see what they called a psoas abscess. On MIP and 3D reconstruction, you can appreciate the stent structure of the endograft. And this was found to be a gore excluder endograft. Briefly, his outside hospital course, he was started on broad-spectrum IV antibiotics. He went to IR for drainage of the abscess, which was found to be negative on gram staining. And then the decision was made to transfer him here to the Cleveland Clinic. The pre-operative assessment that he underwent is as listed, this is fairly standard for these patients on myocardial stress perfusion screening echo, his EF was noted to be 60%. We also tend to do PFTs with baseline and post dilator to see if they have a response as well as PVRs to assess peripheral vascularization.

David Laczynski, MD:
He underwent an explant of the infected endograft. He had a super renal clamp for five minutes with subsequent moving of the clamp infrarenally, and the aortobiiliac bypass with a 20 by 10 rifampin soaked Dacron graft, which was then wrapped with an Omental flat. Here at the Cleveland Clinic we have quite an extensive experience with explantation of these, here's a medley of some of our experience with taking out every one of these grafts in different configurations. And then just briefly, because I know some of my colleagues will touch on this postoperatively he was extubated, transferred to the floor on day three and was able to go home on post-op day nine with long-term suppressive antibiotics. And last we saw him, he was doing well at one month. Thank you very much.

Alex Barnes, PA-C:
Introduce our next speaker, Dr. Englund, to speak more on graft infections.

Kristin Englund, MD:
Today, I'm going to be talking about treatment of the graft with an established infection. So as you've heard with some of the case recap, I'm just going to bring up the most important infectious disease opportunities. So when the patient was admitted about a month after his initial surgery, he did have wound dehiscence and there was purulent drainage coming from his left groin. Blood cultures, though, at that time did grow bacteroides fragilis while they did not feel that the graft was infected at this point in time, he was started on piptazobactam for roughly 12 days, but then was deescalated down to metronidazole. He did stop the oral metronidazole on his own after about two to three days, unfortunately, due to nausea though, it was planned to be continued for much longer than that. So up to this point in time, we've really been treating patients based upon recommendations from case series and from meta-analysis.

Kristin Englund, MD:
But earlier this year, the European society for vascular surgery did come out with a set of practice guidelines for the treatment of vascular graft and endograft infections. And that's what I'm going to be basing a lot of this talk upon. Starting with the first recommendation, we looked at a new set of criteria that they proposed called the MAGIC criteria to evaluate patients as to whether we feel they have an endograft infection. In looking at the criteria placed here, according to the MAGIC criteria, a vascular graft, or endograft infection is suspected in the presence of one major or two minor criteria from each of these three different categories. And the vascular graft infection is diagnosed when there's at least one major criterion and any other criterion from any of the other categories. When we look at the patient preoperatively, we see that he did have localized features of graft infection.

Kristin Englund, MD:
He had an open wound with discharge. He did not have a fever, which many patients may present with. He did have perigraft gas on the CT scan. He also had blood cultures that were positive, but remember these were at the outside hospital. So you have to do your work ahead of time and make sure that you're reaching out to those referring hospitals to get that information because his blood cultures here were negative. And as was mentioned before, he had elevated inflammatory markers with the CRP and sed rate. So possible sources of our endovascular or endograft infections that can occur during the initial placement of the graft. So intra-operative bacterial contamination. They can occur when there's a spread from the infection from a contiguous site, such as a wound infection, the graft can erode into the duodenum or the colon, and there can be bacterial colonization of a thrombus.

Kristin Englund, MD:
One of Dr. Lyden's articles of many also discuss the bacteremia from non graft related infections, as you can see here. And I would strongly suggest that we look at people's teeth when they are admitted to make sure that there aren't any dental abscesses. I think this is a source of infection that usually goes markedly unrecognized. Recommendation two, we're talking about... It's important if you suspect an infection to obtain microbiological proof of infection and to try and obtain at least three deep, rather than superficial samples for a microbacterial detection. Tissue is the issue is the ID motto and explanted graph material or tissue is obviously our best source. And there's the opportunity to take the graft in sonification to help, to be able to get the bacteria off of it better. Perigraft fluid collection, whether it's surgical or interventional radiology is also a good source. Interoperatively, make sure you're avoiding swabs.

Kristin Englund, MD:
Those are not suitable for anaerobes. You remember this patient had a bacteroides fragilis, which is an anaerobe infection, and that would not be picked up if they were using swabs. Blood cultures are often positive in about 35% of the cases as was this patient's. Again, pre-coming to this hospital because our blood cultures here were negative. Swabs from superficial wounds are really not helpful. Even if there's a sinus tract that's present at the outside hospital in June, when he first presented, he had swabs sent from that wound and they grew corynebacterium, and coagulase negative staph, neither of which were involved in his graft infection, ultimately. And vac dressing sponges, don't even bother to culture those. So, it seems intuitive, but the recommendations now are that patients need anti-microbial prophylaxis to cover the first 24 hours during the time of surgery.

Kristin Englund, MD:
But when we look at one of the first articles talking about endograft infections back in 1972, Szilagyi looked at a case series of a number of patients at their institution. And in looking at the organisms in the middle of the page, you can see there was a lot of staph, call it staph at that point in time was not coagulase negative or staph aureus, but it was what was there. And E. coli. So a lot of different skin flora that was found. Around this period of time, they were not using peri-operative antibiotics. So in evaluating where the infections were coming from, recommendations were made at that point in time, that patients should be getting impure peri-operative antibiotics against common skin flora. Thankfully, even though they weren't using peri-operative antibiotics, you can see that the percentage of infections was still under about 3%.

Kristin Englund, MD:
Anti-microbial therapy is recommended in every patient with an infected graft or endograft. And that's certainly based upon looking at the bacteriology that we expect to find. 58% of patients will present with a gram-positive bacteria in their endograft infection, but 34% of them can present with gram negative bacteria. And we're seeing pseudomonas aeruginosa becoming more and more prevalent. And those can be very difficult to treat. As we mentioned with this patient, 8% of cases are anaerobes, and we can certainly see candidal or other fungal infections, the rarely. So for the antibiotic choices, patients are usually initially started on vancomycin and pip-tazo although vanc and cefepime or vanc and meropenem are certainly available for patients who are penicillin allergic. Once we identify the organism, if it's methicillin susceptible staph aureus, it is always best to deescalate them to a beta lactam. And since we anticipate that biofilm is present in an endograft infection, adding rifampin, if it's susceptible staph is appropriate.

Kristin Englund, MD:
Looking at your local resistance patterns is important. Although many of our patients are being transferred in from outside hospitals. So the resistance patterns there may be markedly different. And if you think that there's a visceral fistula, that's important to add antifungal therapy. So as we mentioned and earlier, this patient had a renal dysfunction. So a case series has been looking at daptomycin as a potential alternative for treatment instead of using our vancomycin and actually this case series in the International Journal of Infectious Diseases, it did seem to provide a lot of optimistic information about using dapto and five of the patients with coag negative staph who received both dapto and rifampin were all cured.

Kristin Englund, MD:
Duration of therapy. The current recommendations from the guidelines state that if the prosthetic material and tissue is removed two weeks of IV antibiotics, and up to four weeks of an oral antibiotic are appropriate. If the infected material is replaced with a new vascular graft at that same surgery, a longer time course is necessary with four to six weeks of IV therapy followed by even up to 12 months of an oral tail. For patients who are poor surgical candidates have a multi-drug resistant organism, or there's extensive perigraft infection, lifelong suppression of the antibiotic may need to be considered. We don't see too terribly many endovascular grafts, thankfully, so we can base our time duration of treatment based upon other prosthetic material infections that we see. So say with prosthetic valve endocarditis, we treat for six weeks for our prosthetic joint infections, depending upon the type of surgery that is performed we will also give six weeks of antibiotic therapy, and we follow this with a tail of oral antibiotics, depending upon the joint and the type of procedure that was performed.

Kristin Englund, MD:
Last part of the guidelines that I'm going to recommend is that for patients with multi-drug resistant microorganisms, extra anatomic reconstruction may be considered, and I'll leave that to the surgeons to talk about, but it's important because if there are multi-drug resistant organisms, we need to remember that an oral option for long-term suppression may not be available. So when we look at this algorithm that is proposed talking about the way that we move through to making surgical decisions, I'm going to encourage the team approach that's already been brought up to this point in time. And instead of including us kind of in the end where there's conservative or palliative treatment and prolonged antibiotics being discussed at the very end, our teams are very good about bringing us up right on board initially so we can get patients to a less renal toxic antibiotic, and we can also make sure that we're involved in the discussions about the type of surgery in case we don't have an oral option for our patients.

Kristin Englund, MD:
So teamwork is essential. The patient was initially brought in on vanc and pip-tazo was transferred over to dapto in unasyn, two aortic graft samples were positive for bacteroides fragilis. He received four total weeks of IV antibiotic therapy. We had changed him over to IV amp sulbactam and got rid of the vancomycin early on. And as was mentioned, he's gone home on oral augmentin because he didn't tolerate flagyl before and seems to be doing quite well with it. Thank you very much.

Announcer:
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